Process of manufacture of ammonium nitrate from ammonium sulfate and sodium nitrate.



FRANCIS A. FREIEiTH, OF GREAT- CROSBY, HERBERT COCKSEDGE, OF LONDON,

Y i ENGLAND.

rnocnss or MANUFACTURE or AMMONIUM NITRATE FROM ,AMMONI'UM SULFATE AND SODIUM NITRATE.

No Drawing.

To all whom it may concern Be it known that we, FRANCIS ARTHUR FREETH and HERBERT EDWIN CocKsnDeE,

nium Sulfate and Sodium Nitrate, of which .the following is a specification. hitherto known whereby equivalent quantities of pure amv No method has been monium nitrate and pure sodium sulfate can beyproduced by a continuous process by the greaction between equivalent quantities of ammonium-sulfate and sodium nitrate.

' 'We have discovered a process whereby, by the reaction between equivalent" quantities of ammonium sulfateand', sodium nitrate in the presence of a, liquor of a certain-composition, we can prepare pure or practically pure ammonium nitrate and pure. or practically pure sodium sulfate 1n equivalent quantities and whereby also the liquor in -thepresence of which the reaction is performed is reproduced at the end of. each cycle of operations ready for a fresh cycle.

The process is further distinguished by the fact that no solid other than ammonium;

, nitrate and sodium sulfate is precipitated from solution in any part .of the operations. Our process. depends upon the hitherto unknown fact that when a mixtureof-ammonium sulfate and sodium nitrate in equiy-f alent proportions and in total quantity de-;'

pending upon the conditions under which the subsequent operations are performed, is;

added to a solution; containing sodium nitrate, ammonium nitrate, and sodium sulfate in proportions whichalso-vary with the cone ditions under which the reactions are performed, the ammonium sulfate and the 'sodium' nitrate react with formation of sodium sulfate, which is precipitated unmixed with other salts and is removed from the solution at the temperature selected asthat at which the reaction is to be performed and for which the composition of the solution in v presence of which the reaction" takes place i Our process is conducted as-renown Hav- "is to be cooled for-"separation of ammonium Specification of Letters Patent. 1 Patented Jan, 21, 1913 Application filed June 5, 1911. Serial No. 631,402.

ofthe sodium sulfate precipitated in the pre-' vious operation which after suitable washing to remove mother liquor is pure or prac- 65 tical'l'y pure, and the mother liquor remain- 4 ing after being concentrated by evaporation to an extent suflicient to compensate for the water added just before cooling, has the same composition as the liquor to which the equivalent quantities of sodium nitrate and ammonium sulfate were. originally added, and can be subjected to the same cycle of operations-with the-same results, and so on indefinitely. 7

It is to be understood that where the phrases temperature of reaction, temperature at which the reaction. is performed [are used, they mean the temperature at which the sodium'sulfate precipitated by the reaction is removed from the solution; during the time that the reactionis proceeding the temperature neednot necessarily be the same as this. In the same way the temperature to which the liquor is cooled for separation of ammonium nitrate means'the temperature at which the ammonium nitrate precipitated by the cooling is removedfrom the solution.

ingdecided upon. (a) the temperature. at which the reaction'is-to be performed, (5)

' the temperature to which the liquor is to'be subsequently cooled for separation of am monium nitrate, the initial operation conslsts in preparing a solution saturated with- 'respect' to ammonium nitrate and sodium 7 "nitrate at the temperature towhich the liquor resulting from subsequent operations nitrate and adding tothis sodium s'ulfate until no-more will "dissolve at that same' temperature,that is, until the double salt 3NH,NO .(NH ),SO

just begins to form. This solution is saturated with respect to ammonium nitrate, sodium nitrate and the double salt at the above temperature and will be referred to as the nucleus solution. The nucleus solution is then raised to the temperatureat which the reaction is to be performed and equivalent quantities of ammonium sulfate and sodium nitrate are added, with stirring, in such quantity that, after the reaction is finished the ratio of sodium nitrate to ammonium nitrate in the resulting solution at the temperature of reaction is the same as'that which obtainsln a solution saturated at the temperature of reaction with respect to the double salt 3NH NO (NIL) SO and with sodium sulfate, when such solu tion contains sodium nitrate and sodium sulfate in the same ratio as obtains 1n the nucleus solution. The stirring is continued and the mixture concentrated by evaporation until the ratioof sodium nitrate to sodium, sulfate in solution is actually the same as that. of the nucleus solution, the change in'ratio being effected by the further deposition of sodium sulfate. The precipitated sodium sulfate is then separated from the solution at the temperature of reaction and'washed to free it from adherent mother liquor, when it is practically free rated solution of ammonium nitrate to free it from adherent mother liquor and dried by any well-known means, when it is pure or practically pure. The mother liquor re:

inaining then has the same-or practically the same composition as the original imcleussolution; it is subjected-to a fresh cycle of operations 'bybeing concentrated by evaporation to an extent sufiicient to remove a quantity of Water equal to that s which was added in the previous cycle after separation of the precipitated sodium $111- which may have been caused by wash liquors fate and to compensate for any dilution 4 or otherwise. To the liquor, either before,

during or after concentration, equivalent quantities of ammonium sulfate andsodium nitrate are added to an, amount equivalent,

to the ammonium nitrate which has been removed by cooling in the previous cycle, ex-

cept that it may be necessary to make someslight adjustment of the quantities to compensate for addition of wash liquors, etc. The reaction proceeds as before, and the sodium sulfate and ammonium nitrate are formed and, recovered as previously described. This cycle of operations maybe repeated indefinitely, or until the liquors have become so impure that it is necessary to renew them. If the temperature at .which the ammonium nitrate isrem oved from the solution is alwayskept the same, the motherliquor resulting from it always has the same composition and requires the same; treatment to prepare it. for another cycle.

We have found, as already mentioned, that the process is best performed under such conditionsthat in the solution remain-v ing after separation at'the temperature of reaction of the sodium sulfate (resulting from the reaction between the equivalent quantities of ammonium sulfate and sodium nitrate added ,to the nucleus solution with which the process starts, or in subsequent cycles, to the mother liquor after separation of ammonium nitrate), the same ratio of sodium sulfate to sodium nitrate obtains at thetemperature of reaction as obtains in the mother liquor resulting from the opera-' tion of cooling and separation of ammonium nitrate, that liquor being saturated with respect to ammonium nitrate and also saturated or practically saturatedwith re-' spect to sodium nitrate and with the double at the temperature to which the liquor was cooled. This ratio necessitates'the .addition of the minimum quantity of water before. cooling, but the process may be worked with a somewhat diflerent proportion of sodium nitrate to sodium sulfateat -fthe .cost'pf an increased addition of watenbefore-cooling and consequently of greater evaporation subsequently. If, for any reason, such as i the addition of too much water, the ammonium nitrate separated from the solu-' tion ,on cooling is less than-that quantity which is equivalent to the sodium sulfate separated in the. same cycle, then come spondi'ngly smaller equivalent quantities of ammoniumsulfate and sodium nitrate must be added to the motherliquor in the succeeding cycle, otherwise the doubleisalt 3N H NO (NH SO would separate out with the sodium sulfate and contaminate it.

. EmempZes, v i

(A When the temperature at which the reactlon is to be performed is 45 centimother liquor remaining 7 To it, at

i The sodium sulfate 'andQQ/Z of sodium sulfate, this solution being saturated with respectto ammonium nitrate, sodium nitrate and the double salt 3NH NO (NH SO at 20 C. This solution is then raised to about the temperatur'e of the reaction and llf) parts tor ammonium sulfate and 53.9 parts offsodium nit-rate are added to it, the mixture'stirred, and when the reaction is completed or while it is proceeding 23.1 parts of water are evaporated from it for every 100 parts of water originally present.

precipitated is then separated 'at45 cent-igrade and to the solue tion remaining water is added until the rat-i0 of sodium nitrate-to water is the same as it was in the original nucleus solution. This liquor is then 'cooledto 20 centigrade, when it deposits 50.8 parts by weight of ammonium nitrate for every 100 parts by weight of water containedin it. The ammonium nitrate deposited is separated from the solution at 20 centigrade and the then has the same compositlon as the original nucleus solution and is employed for a. fresh cycle of operations as already explained. k

(13.) When the reaction is to be performed at 40 oentigrade and the temperature to which the liquor is to be cooled for separation of ammonium nitrate is 20? centigrade, a nucleus solution is prepared identical in composition with that given in example A. about the temperature of reaction are added 345.2 parts of ammonium sulfate and 4A parts of sodium nitrateper 100 parts of water present in it and 16.3 parts of water per 100 contained in it are evaporated.

added to the liquor remaining until the ratio 'of water to-sodium nitrate is the same as that of the nucleus solution; this liquor is then cooled to 20 centigrade when 41A parts of ammonium nitrate are deposited per 100 parts of The ammonium nitrate deposited is separated from the solution at 20 centigrade, and the. mother liquor-remaining has the same composition as the original nucleus solution and is employed for a fresh cycle of operations as already explained.

lVe declare that what we claim is:

1. The process for manufacturing practically pure ammonium nitrate from ammonium sulfate and sodium nitrate, which water contained -m it.

consists in preparing a solution (hereafter called the nucleus solution) saturated with respect to ammonium nitrate and sodium nitrate at the temperature to which the liquor resulting from subsequent operations is arranged to be cooled for separating the ammonium -nitrate, a-nd adding to this, sodium sulfate, until no more will dissolve at that same temperature, that is, until the double salt just begins to form, raising the temperature of this nucleus solution to the'temperature at which it has been arranged the reaction shall be performed, and adding equivalent quantities of ammoniumsulfate and sodium nitrate with stirring, in such quantity that after the reaction is finished, the ratio of sodium nitrate to ammonium nitrate in the resultingsolution at the temperature of reaction, is the same as that which obtains in a solution saturated at the temperature of reaction with respect to the double salt 1 7 a a or at a,

and withsodium sulfate, when such solution contains sodium nitrate and sodium sulfate in the same ratio as obtains in the nucleus v solution; continuing the stirring and concentrating the mixture by evaporation until the ratio of sodium nitrate to sodium sulfate in solution is actually the same or nearly be same as that in the nucleus solution employed, thereby precipitating sodium sulfate; separating .the precipitated sodium sulfate from the solution at the temperature originally decided upon, and for which the quantities and compositionof the liquors employed have been adjusted,jand'washing the sodium sulfate to remove adherent mother liquor; adding water to the solution from which the pre-' tion to the temperature originally decided upon for separation of ammonium nitrate, for which temperature the quantities and solutions employed have been adapted; separating the preci itated ammonium nitrate from the solution at that temperature,

washing it with a substantially saturated solution of ammonium nitrate to free it from adherent mother liquor, and drying it by any well-known means.

2. The improvement in manufacturing practically the process for pure ammonium nitrate from ammonlum sulfate and sodium nitrate, which consists in allowing to react 1n the presence of a solution containing sodium sulfate SOdlllIIl'IllilliliiG and ammonium lnitrate, such quantities of sodium nitrate and ammonium sulfate as will yield when the reaction is finished a solution saturated w1th respect tojsodium sulfate and the double salt a Y i' 3) (N JQ lution saturated with respect to ammonium nitratefsodium nitrate and thedouble salt mam nng so,

i he temperature at whichi'it is subseiy proposed to remove the ammonium nitratli i'ermed by the reaction,-separating '20 solution from whichthe sulfate has been removed until the ratio of nium nitrate,

. salt the sodium sulfate at the temperature for which the above quantities andsolutions have been adjusted, Washing it to remove adherent'mother liguor,'adding water to the precipitatedsOdium water to' sodium nitrate is the same as or slightly greater than that which obtains in a solution saturated with respect to ammosodium nitrate and the double a in s-(Mat cooling the resulting solution to this temperature, separating the precipitated ammonium nitrate,

washing it'w'ith a substantially saturated solution of ammonium nitrate, drying it by any well l m'own means and concentrating the remaining mother liquor to an extent consists in adding samecompositionas repeating the above operations indefinitely.

' at the temperature oftthe subsequent. re- 30' moval-of ammonium nitrate,

suflicient to remove the quantity .of extra water added before the precipitation of amoperations indefinitely.

The process for the manufacture of practically 'pure ammonium nitrate which ammonium sulfate 53.9. parts of sodium nitrate to 342.5-parts of a solution containing 186 parts of ammonium nitrate, 56.9 parts of sodium nitrate,'22.7 parts ofsodium sulfate and 76.9 parts of water, stirring the same at-a temperature of .45 0;, and at the completion of the reaction fate formed at that temperature,adding to the mother-"liquor remaining 23. 1- parts of water per 56.9 parts of sodium nitrate present; cooling the same to 20 (1., separating the ammonium nitrate formed,- washing it with a vsubstantially saturated solution of ammonium nitrate and drying it by any well-known means; concentrating ithe solution remaining. until-it has substantially the the initial solution, and

' In witness whereof, we have hereunto signed ournames this 25 day of May 1911, in the presence of two subscribing witnesses.

I F. A, FREETH.

H. E. COCKSEDGE.

Witnesses; WILLIAMS, H. 0. Dixon.

separating the sodium sulequivalent quantities of I and sodium nitrate, 'namely, 41.9 parts of ammonium sulfate and 

